OSS trident: fix locking around write_voice_regs

trident_write_voice_regs() was getting called with the card spinlock held in
only some cases.  Fix it.

Explanation: we allocate a new virtual channel in open, and then we frob some
hardware registers (in write_voice_regs) for that channel.  But the hardware
registers are shared with other channels, which may be trying to frob the some
registers (albeit for another channel) via ioctl(SNDCTL_DSP_SPEED).

Fixed bugzilla.kernel.org bug #8172 (http://bugme.osdl.org/show_bug.cgi?id=8172)

Signed-off-by: Muli Ben-Yehuda <muli@il.ibm.com>
Cc: <tammy000@gmail.com>
Cc: <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 5 insertions, 0 deletions

diff --git a/sound/oss/trident.c b/sound/oss/trident.c
index 3e408f491927..2e3e78e1bf67 100644
--- a/sound/oss/trident.c
+++ b/sound/oss/trident.c
@@ -2702,6 +2702,7 @@ trident_open(struct inode *inode, struct file *file)
         struct trident_card *card = devs;
         struct trident_state *state = NULL;
         struct dmabuf *dmabuf = NULL;
+        unsigned long flags;
 
         /* Added by Matt Wu 01-05-2001 */
         /* TODO: there's some redundacy here wrt the check below */
@@ -2779,7 +2780,9 @@ trident_open(struct inode *inode, struct file *file)
                         /* set default channel attribute to normal playback */
                         dmabuf->channel->attribute = CHANNEL_PB;
                 }
+                spin_lock_irqsave(&card->lock, flags);
                 trident_set_dac_rate(state, 8000);
+                spin_unlock_irqrestore(&card->lock, flags);
         }
 
         if (file->f_mode & FMODE_READ) {
@@ -2797,7 +2800,9 @@ trident_open(struct inode *inode, struct file *file)
                         dmabuf->channel->attribute = (CHANNEL_REC | PCM_LR |
                                                       MONO_MIX);
                 }
+                spin_lock_irqsave(&card->lock, flags);
                 trident_set_adc_rate(state, 8000);
+                spin_unlock_irqrestore(&card->lock, flags);
 
                 /* Added by Matt Wu 01-05-2001 */
                 if (card->pci_id == PCI_DEVICE_ID_ALI_5451)